BOUILLIE BORDELAISE. 



241 



TABLE XLII. — Sound Plants, Showing Number, Weight, atid Size of Large 

 and Small Potatoes before the Appearance of Disease. 



TABLE XLIII. — Diseased Plants, Showing Number, Weight, and Size of Large 

 and Small Potatoes after the Appearance of the Disease. 



According to this table the untreated sound plants, i.e. the tubers 

 of which were lifted before the disease appeared, gave a greater yield 

 of tubers than those treated with bouiUie bordelaise. Sorauer explains- 

 this fact by a certain degeneration of the leaf, very characteristic, 

 which is the result of treatment with cupric compounds. This, 

 degeneration is especially pronounced when the bouillie used still, 

 contains unconverted blue vitriol, or when sprayings are made with 

 a soluble salt such as acetate of copper. Sturgis got the following- 

 results with various copper preparations : — 



TABLE XLIV. — Showing the Effect of Various Copper Preparations on the: 

 Bulk of the Potato Crop, and the Number of Diseased Potatoes. 



Sorauer advises not to spray early varieties, generally lifted before 

 the disease develops in a threatening manner, for the treatment would 

 not only be useless, but might lower the weight of the crop. Frank 



16 



